Thermal energy storage and retrieval systems and methods

Abstract

The invention provides, in some aspects, a thermal energy storage and retrieval system with a cavity containing a working fluid and a heat transfer surface disposed in the cavity transverse to a gravity field and in thermal coupling with an ice that is formed from and floating in the working fluid. The heat transfer surface transfers to that ice heat from a heat transfer medium that is thermally coupled to the heat transfer surface. According to aspects of the invention in which the ice is less dense than the working fluid, the heat transfer surface is disposed above (with respect to the gravity field) a region of the cavity where that ice is formed or inlet. According to aspects of the invention in which the ice is more dense than the working fluid, the heat transfer surface is disposed below that region.

In view of the foregoing, what I claim is: 
     
       1. A thermal energy storage and retrieval system, comprising
 a cavity containing a working fluid, 
 a condensing surface disposed in the cavity in thermal coupling with the working fluid, wherein the condensing surface repeats a plurality of times a cycle that includes steps of 
 (a) cooling the condensing surface to form ice from the working fluid on the condensing surface, and 
 (b) heating the condensing surface to detach ice buildup from the condensing surface to float in the working fluid, 
 a heat transfer surface disposed in the cavity transverse to a gravity field and in thermal coupling with the ice that is formed from and floating in the working fluid, 
 the heat transfer surface transferring to the ice heat from a heat transfer medium that is thermally coupled to the heat transfer surface, 
 the heat transfer surface being disposed above, with respect to the gravity field, a region of the cavity where said ice is formed, if the ice is less dense than the working fluid, and otherwise being disposed below that region. 
 
     
     
       2. The thermal energy storage and retrieval system of  claim 1 , wherein the heat transfer medium is a fluid. 
     
     
       3. The thermal energy storage and retrieval system of  claim 2 , wherein the heat transfer medium is isobutane. 
     
     
       4. The thermal energy storage and retrieval system of  claim 2 , wherein the heat transfer medium flows through the heat transfer surface to exchange heat with the ice. 
     
     
       5. The thermal energy storage and retrieval system of  claim 4 , wherein the heat transfer surface comprises one or more channels through which the heat transfer medium fluid flows in thermal coupling with the ice. 
     
     
       6. The thermal energy storage and retrieval system of  claim 1 , wherein the working fluid is water. 
     
     
       7. The thermal energy storage and retrieval system of  claim 1 , wherein the heat transfer surface is disposed below a surface of the working fluid in the cavity, if the ice is less dense than the working fluid, and otherwise is disposed above a bottom of the cavity. 
     
     
       8. The thermal energy storage and retrieval system of  claim 7 , wherein the heat transfer surface includes at least one recess to capture ice of the working fluid floating in the working fluid. 
     
     
       9. The thermal energy storage and retrieval system of  claim 8 , wherein the at least one recess prevents the ice from reaching a surface of the working fluid, if the ice is less dense than the working fluid, and otherwise prevents the ice from reaching the bottom of the cavity. 
     
     
       10. The thermal energy storage and retrieval system of  claim 1  operable in (i) a charging mode in which ice is aggregated within the cavity, and (ii) in a discharging mode in which heat from the heat transfer medium is transferred to the aggregated ice to cool the heat transfer medium and to convert the ice to working fluid.